This invention relates to power transmissions and more particularly to power transmissions having multiple countershafts. Specifically, this invention relates to a dowel and seal ring structure which provides for alignment of the countershafts, an end support plate and a bell housing or engine mount and oil passages for lubrication and clutch feed.
Power transmissions with multiple countershafts generally have a housing assembly formed with at least two members that are aligned by dowel pins. These members generally include a casing and an end cover or bell housing. The bell housing generally encloses a torque converter or friction clutch. The countershafts are supported in the casing at one end and in the end cover at the other end. The input shaft is generally supported in the end cover and the output shaft is supported in the casing.
The alignment and parallelism of the shafts is determined by the doweling between the casing and cover and the bearing bores in each of the casing and end cover. The machining of the required dowel and bearing bores is subject to manufacturing tolerances which must be held within close limits for quiet, efficient and durable operation of the transmission. As is well known, close tolerance machining adds to the overall cost of the product.
A further disadvantage of the prior art is the need for an inspection opening which permits visual inspection during assembly. This opening usually is provided in the bottom of the casing and is covered by a pan which is secured to the casing by fasteners during final assembly. A gasket must be installed between the casing and the pan to ensure against fluid leakage from the assembly. More than one inspection port has been provided in the prior art, and each of these ports must be closed with a gasket, cover and fasteners which, of course, add to the overall cost.